1. Field of the Invention
The present invention relates to the treatment of liquids and, more particularly, pertains to a method and apparatus for filtering liquids.
2. Description of the Prior Art
It is well known to filtrate a liquid by supplying the same to a bed of particulate filter media contained in a tank having a truncated conical bottom end portion configured to prevent the formation of stagnant or dead zones within the bed of particulate filter media. For instance, U.S. Pat. No. 4,126,546 issued on Nov. 21, 1978 to Hjelmner et al. discloses a sand filter comprising a main tank having a funnel-like shape bottom portion. The geometry of the main tank results in the filter being relatively tall which presents a number of disadvantages. The liquid to be filtered is delivered along a vertical direction into the sand and passed gradually upwardly therethrough to form a pool of filtrated liquid above the top surface of the bed of sand. Deflectors must be provided to prevent particles of sand to come in direct contact with the outlet end of each delivery pipe used to supply the liquid to be treated. A single central transport device is provided to continuously convey dirty particles of sand from the bottom of the tank to a washing device immersed in the pool of filtrated liquid. The dirty particles flows downwardly through a single annular wash path defined in the washing device in counter-current with a wash liquid before being recycle onto the top of the filter bed. A deflector is provided underneath the washing device to distribute the cleaned particles of sand on the top surface of the filter bed.
Although the sand filter described in the above mentioned patent is effective, it has been found that there is a need for a more compact and lightweight filter which is adapted to provide an improved distribution of a particulate filter media.
It is therefore an aim of the present invention to provide a relatively compact and lightweight filter for filtering a liquid by causing it to flow through particulate filter media.
It is also an aim of the present invention to provide a filter which allows continuous washing of the particulate filter media and effective distribution thereof.
It is a further aim of the present invention to provide an improved washing device for continuously washing dirty particles of filter media.
Therefore, in accordance with the present invention, there is provided a filter for filtering a liquid by causing the same to flow upwardly through a particulate filter media, comprising a main tank, at least two upstanding sub-recipients integrated within the main tank for containing a particulate filter media adapted to filter a liquid seeping therethrough, inlet means for delivering and distributing the liquid to be treated into the sub-recipients, and outlet means disposed above a top surface of the sub-recipients for discharging the liquid as a filtrated liquid. The provision of the sub-recipients allows to reduce the height of the filter.
In accordance with a further general aspect of the present invention there is provided an apparatus for filtering a liquid comprising a main tank, at least two laterally separate beds of particulate filter media contained in respective sub-recipients integrated within the main tank, inlet means for delivering a liquid to be treated into both sub-recipients, and outlet means for discharging the liquid which has seeped through the beds of filter media.
In accordance with a further general aspect of the present invention, there is provided a device for washing particulate filter media contaminated during filtration of a liquid, comprising a hollow body defining a wash path, filter media inlet means for directing a flow of dirty filter media in a downward direction along the wash path, washing fluid inlet means for receiving a flow of wash liquid in counter-current to the filter media along the wash path, and a plurality of axially spaced-apart arrays of agglomeration breaking members distributed along at least a portion of the wash path, each array including a number of side-by-side agglomeration breaking members extending across the wash path.